The combined administration of a live PRRS vaccine (UNISTRAIN® PRRS) and a PPV and SE vaccine (ERYSENG® PARVO) reduces viraemia and vertical/horizontal transmission following a heterologous PRRSV challenge.

The combination of two immunological veterinary medicinal products manufactured by HIPRA -UNISTRAIN®PRRS and ERYSENG® PARVO- has successfully been registered in Europe. When combining a live PRRS vaccine with a PPV and SE vaccine, the most important marker of effective protection is demonstration that the PRRS vaccine remains alive and active in combination. Unlike other companies, HIPRA has proven the viability of the PRRS vaccine in combined use with UNISTRAIN® PRRS and ERYSENG® PARVO and, in so doing, it has demonstrated the efficacy of this combination against PRRSv , SE and PPV.

A major concern in PRRS management is the ability of a given vaccine to control viraemia. The study described below demonstrates that gilts vaccinated with the combination of UNISTRAIN® PRRS and ERYSENG® PARVO results in better control over viraemia versus non-vaccinated gilts after a heterologous challenge.

The animals used in this trial were clinically healthy six-month-old gilts free from antibodies against PPV, E. rhusiopathiae and PRRSV. The animals were divided into two groups: a vaccinated group and a control group. The animals in the former group were vaccinated seven weeks before mating with ERYSENG® PARVO (2 ml/dose) and revaccinated four weeks before mating with the combination of UNISTRAIN® PRRS and ERYSENG® PARVO (2 ml/dose). The control group remained unvaccinated. All gilts were challenged with a heterologous pathogenic PRRSV strain at 90 days of gestation, as this is the time when gestating sows are most sensitive to PRRSV. All the animals were sampled before challenge, after challenge and after birth to assess the progression of viraemia and the vertical/horizontal transmission to piglets by RT-PCR.

The results obtained showed that all gilts were negative for viruses after vaccination. After challenge, viraemia was observed in all non-vaccinated animals (100%), while in the vaccinated group, two gilts were positive in two independent samples. The length of the viraemic period was significantly shorter in the vaccinated group (2.5 days) than in the control group (16.9 days).

Vertical transmission of PRRSV to piglets was significantly inhibited in the vaccinated group (6.3% of piglets tested positive for PRRSV at birth) in comparison with the control group (65.9%). Horizontal transmission between piglets during the lactation period was lower in the vaccinated group, as all vaccinated piglets were free of PRRSV when weaned, while 51.5% of piglets in the control group tested positive for PRRSV when weaned.

Vaccination with the combination of UNISTRAIN® PRRS and ERYSENG® PARVO significantly reduced the length of viraemia and vertical/horizontal transmission to piglets after field infection. Therefore, the combination has been proven to reduce PRRSV infection pressure on farms and help stabilise farms faster.